Thesis (Ph. D.)--University of California, San Diego, 1998. / Includes bibliographical references (p. 197-209).

Two biomarkers, n-alkanes and alkenones, have been studied for the distribution of their relative concentrations spatially and temporally in sediments in the Pearl River Estuary. 59 modern sediments have been collected across the Pearl River Estuary and offshore Hong Kong, covering a wide range of environmental and sedimentary conditions. The relative abundances between long-chain (C27 to C33) terrestrial-derived n-alkanes, and short-chain (C18 to C22) n-alkanes which are ascribed to marine algal and bacterial production, have been analyzed as “terrestrial-to-marine n-alkane ratios”. Results show that this ratio follows a general gradient of increasing towards uplands. More detailed interpretation has revealed that this ratio is highly dependent on the proximity of the sampling site to the supply of terrestrial matters, i.e., to river mouths and lands. This finding provides fundamentals on the development of terrestrial-to-marine n-alkane ratio as a potential new proxy for terrestrial sediment flux. The newly developed potential environmental and climate proxy, the relative abundances of n-alkane compounds, is applied on analysis of a sediment core drilled in coastal marine environment offshore Hong Kong, HKUV11, which can be dated back to c. 11,000 yr BP. Alkenone unsaturation ratios are also analyzed to reconstruct post-Younger Dryas change in sea surface temperature (SST). Records show a rapid warming of the ocean surface at the start of the Holocene epoch from c. 11,000 yr BP to c. 9000 yr BP, during when the SST researched its optimum, followed by a long period of more stabilized temperatures with the presence of some short-term cold events. The terrestrial-to-marine n-alkane ratio matches well not only with the alkenone SST data in this study, but also with the bulk organic carbon geochemical data and grain size analysis of HKUV11. This suggest that the n-alkane ratio is a reliable proxy for terrestrial sediment supply in this coastal and estuarine environment, as supported by both the field studies of its natural distribution across the environmental gradient, and the successful application on an actual sediment core. The Holocene climate variability of coastal south China recovered by the HKUV11 sediment record has been compared with δ18O records from a Dongge Cave stalagmite, a Greenland ice core and the Northern Hemisphere summer insolation variability. Results show that late-Glacial to Holocene climate in coastal South China generally agrees with the trend in the distal high-latitude North Atlantic, suggesting a strong external driving force of global climate change by the NH summer insolation variability. A detailed comparison between the HKUV11 SST record and Dongge Cave Asian monsoon record reveals that the temperature in coastal south China is sensitively correlated to the strength of Asian monsoon. These results have important implications to how monsoonal winds and temperature are coupled together, and can provide insights to how they may interact under future climate change in this densely-populated region. / published_or_final_version / Earth Sciences / Master / Master of Philosophy

published_or_final_version / Earth Sciences / Master / Master of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

No description available.

The reconstruction of past environmental conditions is a fascinating research area that attracts the interest of many individuals in various geological disciplines. Paleoenvironmental reconstruction studies can shed light on the understanding of past climates and are a key to the prediction of future climate changes and their consequences. These studies take on special significance when focused on areas sensitive to climate change. The Arctic region, which is experiencing dramatic changes today in its peatlands and in its ocean, is prime example. The entire region plays a major role in global climate changes and has recently received considerable interest because of the potential feedbacks to climate change and its importance in the global carbon cycle. For a better understanding of the role of Arctic peatlands and the Arctic Ocean to global climate changes, more records of past conditions and changes in the region are needed. This work applies different geochemical proxies, with special emphasis on lipid biomarkers, to the study of a permafrost peat deposit collected from the Eastern European Russian Arctic and a marine core retrieved from the Lomonosov Ridge in the central Arctic Ocean. The results reported of this study show that molecular stratigraphy obtained from the analysis of lipid biomarkers in both peat and marine profiles, combined with other environmental proxies, can contribute significantly to the study of Arctic ecosystems of the past. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>

From measurements of thermal and electrical conductivities of 64 ocean sediment samples obtained from piston cores taken off the Oregon Coast, and from 37 water-saturated sandstone samples analyzed by Zierfuss and Van der Vliet (1956), as well as 51 thermal conductivities and water contents of ocean sediments analyzed by Ratcliffe (1960), this research shows that a useful relationship can be obtained giving thermal conductivity when electrical conductivity is known. Analysis of the data was made using theoretical concepts which have been known for many years to relate thermal and electrical conductivity to porosity. The results of this research may make possible a convenient determination of in situ thermal conductivity that would give the average conductivity in materials containing large variations in conductivity. / Graduation date: 1966

Sediments on the inner portion of the Oregon continental shelf consist of clean, well-sorted, detrital sand. This sand has an average median diameter of 2.53Φ (. 173 mm) and is both positively and negatively skewed. Deposits with median diameters in the coarse sand and gravel classes occur at depths of 20 to 40 fathoms and probably represent ancient beach or fluviatile deposits formed during lower stands of sea level. The outer shelf and upper slope are covered by poorly sorted sediments with median diameters in the fine sand to fine silt classes. Mean diameters of the sediments are almost always smaller than their median diameters and the sediments are positively skewed. The heavy mineral assemblages are dominated by the amphibole and pyroxene groups and the opaque-garnet association. Pyroxenes are most abundant in the coarser-grained sediments of the inner shelf and decrease in abundance offshore. Amphiboles are most abundant in the finer-grained sediments of the outer shelf and upper slope. Highest concentrations of the opaque-garnet association also are found in the inshore samples. Sediments of the continental shelf are derived from two principal sources, rivers and erosion of coastal terrace deposits. Rivers are probably contributing only fine-grained material to the shelf as much of the coarser fluviatile material is thought to be trapped in the estuaries. The terrace deposits are actively being eroded and are thought to contribute about 21,000,000 cubic feet (.00013 cubic miles) of sediment to the continental shelf annually. Evidence suggests that much of the inner-shelf sand is probably a relict transgressive sheet sand that was deposited during the last rise in sea level. Most of the deposition of the modern sand on the shelf has been confined to the inner portion of the inner shelf. Finer-grained sediments have been deposited on the outer shelf and upper slope. Characteristics of the sediments on the present continental shelves may be useful in identifying continental shelf deposits in the geologic column. / Graduation date: 1966

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1987. / Bibliography: leaves 150-164. / xiii, 164 leaves, bound ill. 29 cm